For the love of God, whatever you do from here on out, stop treating near-syncope as the inferior version of syncope. Just stop. Stop now. I mean it. I have a stick. If you take nothing else from this podcast, leave with the understanding that the same mechanisms, lethal mechanisms, cause both syncope and near syncope. Despite my deep protesting now, I do believe that it is important for us to take a second and define the accepted understanding of near-syncope and syncope.

According to Tintinalli’s Emergency Medicine Manual, syncope is “a transient loss of consciousness accompanied by loss of postural tone, followed by complete resolution without intervention”. In contrast, Merck Manual defines near-syncope as “light-headedness and a sense of an impending faint without loss of consciousness”. Neither one of these definitions are groundbreaking or illuminate your current understanding of syncope. What should concern us about syncope is the vagueness of surrounding circumstances that accompanies it and the amount of life-threatening situations that often present with few other symptoms beyond syncope. As we talked about in our last episode, MAAAYYYBEEE We’re Not Great at Spotting Atypical Strokes, posterior strokes are often not picked up by our standard use of the Cincinnati Prehospital Stroke Scale (CPSS). In fact, they often present with feelings or vertigo-like symptoms or near-syncope. There’s that friggin’ term, again.

To be clear, syncope can be caused by non-fatal events; there is no debating that, however, in prehospital care, we have become lazy (or perhaps ignorant) while searching for causes of syncope. We will briefly touch on things like micturition and vasovagal syncope, but that is not the main focus of this episode. The main focus will be talking about the cardiac causes of syncope, as well as discussing things like the Rules of 15s and the CHESS syncope mnemonic. For further explanation, we will be referring to both near-syncope and syncope as syncope to avoid any confusion.

Fairly benign, doesn’t typically call for an admission for patients with no other significant comorbidities.

Vasovagal Syncope

Vasovagal syncope is syncope that is usually tied into an emotional or external stressor.

Often likened to “pseudo-seizure” activity.

Can be caused by things like pain, having blood drawn, being overheated, etc.

Referred to often as neurocardiogenic syncope.

Fairly benign, doesn’t typically call for an admission for patients with no other significant comorbidities.

Postural Hypotension and Orthostatics

Hypovolemia is a cause of syncope and postural hypotension should be considered; this is going to be identified through a good history and physical examination. In fact, all of these types of syncope is identified through a good history and physical examination.

Stop doing routine orthostatic vital signs on patients that you suspect of hypovolemia! If you sit up a patient and they are dizzy, they are orthostatic!

Watch this short video by Core EM’s Anand Swaminathan debunking the myth of orthostatic vital signs.

A Quick Note on Pediatric Syncope Assessment

For reasons that we will get into later, it is of great import to figure out immediately if your pediatric patient had a seizure, a breath holding spell, or a true syncopal episode. Do no kid yourselves, pediatric syncope is linked to a markedly higher mortality rate than adult syncope.

Differentiating Between Syncope and Seizures

There is a considerable amount of dogma in reference to seizure and syncope recognition, so let’s talk about some of it.

Syncope can incorporate brief muscle spasms that can mimic a seizure.

Patients who experience syncope can have a loss of bladder or bowel.

Patients at risk for seizures typically have risk factors like diabetics, pre-eclampsia, etc.

Patients that have seizures typically have injury patterns that syncope patients do not; i.e. soft tissue injury, especially in the mouth, or widespread bruising in multiple different locations.

20% of patients that were examined and initially diagnosed with a simple epileptic episode were later on diagnosed with a cardiac event leading to syncope. Even experienced providers misdiagnose syncope as seizures.

It is extremely rare for patients with seizure disorders to have syncopal episodes. In fact, of the number of syncope patients that were evaluated, only 3/797 patients had a concurrent seizure history.

Cardiac Causes of Synope

We will be breaking down some significant cardiac causes of syncope; it is important to note that cardiac induced syncope can be life-threatening. Every true syncopal patient needs a 12-lead. A great mnemomic device put forth by the EM Clerkship Podcast about syncope was QT-Bride. Here are some examples of what our syncopal patients’ 12-lead leads could look like in the field.

Picture Courtesy of American Board of Family Medicine.

Brugada

Causes: According to the NIH, “Brugada syndrome is a condition that causes a disruption of the heart’s normal rhythm. Specifically, this disorder can lead to irregular heartbeats in the heart’s lower chambers (ventricles), which is an abnormality called ventricular arrhythmia.”

Identification:

“Coved” ST Elevation >2mm in V1-V3 (LITFL)

Population at Risk

Infants, young adults, and those around 40yo; also a markedly higher risk factor for those of SE Asian descent.

Much more likely in men than women (8:1 ratio)

Occurs in approximately 5/100,000 people worldwide

Definitive Treatment

AICD Placement due to high incident of progression into lethal ventricular rhythms.

Right Heart Strain

Common causes of this are pulmonary embolism, pulmonary hypertension, cor pulmonale, and arrythmogenic right ventricular cardiomyopathy.

The right side of the heart becomes massively overwhelmed and is unable to generate adequate preload; whether it is a clot or muscular failure, this is a huge finding on an EKG.

Most common EKG finding in right heart strain is going to be ST depression or T wave inversion in V1-V4.

Photo Courtesy of Life in the Fast Lane

Ischemia/Infarction

A 2009 Study in the Canadian Journal of Emergency Medicine discussed the prevalence of classic syncope in the presence of AMI. Out of the 1,474 patients that were monitored, only 42 (0.03%) were actually diagnosed with AMI.

Out of those 42 patients, 37 of them presented with NSTEMI.

In contrast, a 2000 study in the European Journal of Clinical Investigation yielded a 13% likelihood of near syncope in patients that were evaluated during AMI discovery.

The conclusion of the study suggested that patients with AMI diagnosis are at risk for neuromediated reactions, i.e. near syncope.

Clinical caveat of note:

Patients that are experienced Right Ventricular MIs are at higher risk for syncope due to significant hypotension and highly increased vagal tone.

Delta Waves

Causes

Delta waves are often benign; the most likely cause of a delta wave is Wolff-Parkinson-White (WPW)

Delta waves are essentially upslopes prior to the QRS complex; they can have positive and negative deflections.

Identification

Retrospective study in PACE reveals that 22% of surveyed patients with WPW presented with exacerbation with primary symptom being syncope.

Estimates range from 0.1-3/1,000 patients that are evaluated.

Associated with small risk for sudden cardiac arrest.

Best treatment modalities are typically procainamide or synchronized cardioversion.

Due to the preexcitation of the AV Node, patients that have been diagnosed with WPW are at risk for ventricular tachydysrhythmias.

Most prominent occurrence of this is during Afib with WPW.

Treatment of patients with Afib with simultaneously occurring WPW that are treated with beta/calcium channel blockers or adenosine can quickly convert into VF or VT.

Approximately 10% of EKGs that initially diagnosed as SVT in pediatrics are actually Afib with WPW.

Photo Courtesy of Case Studies in EKG Pathology.

Epsilon Waves

Largest leading causes of epsilon waves is Arrythmogenic Right Ventricular Cardiomyopathy (ARVC).

Can be found in symptomatic diagnosis of BBB (right and left).

The main presentation for ARVC and symptomatic BBB discovery is… you guessed it, syncope.

Epsilon waves are characterized by positive deflections at the end of a QRS complex.

ARVC and Syncope:

Effects 1 in 1,500 patients

3:1 Ratio of men to women

Associated with 20% of cardiac related deaths in people <35%

Often is accompanied by paroxysmal VT

Typically presents with T-Wave inversion in V1-V3

Caused by muscle that is replaced by adipose tissue

Tachydysrhythmias in Syncope

SVT/PSVT/AVNRT (Whatever the hell you refer to it as…)

We all jump to SVT as a common cause in syncope while thinking of tachydyrhythmias, however, the literature may say otherwise.

There is a fair amount of debate surrounding the ability for atrial fibrillation or atrial flutter causing syncope, however, there is a great article from the Journal of Atrial Fibrillation that discusses this. This certainly ties into the idea of right heart strain and right heart failure.

Photo Courtesy of Teaching Medicine

Ventricular Fibrillation

VF can cause syncope? Truthfully, I have found myself laughing while going through ACLS recertification scenarios and hearing people talk about VF as a cause of hemodynamic instability in a patient that is conscious during the scenario. VF means you’re dead. However, that is not always the case. There have been a few documented case studies about patients with VADs having had syncopal episodes, but will be conscious while in active VF. For fear of digressing further, we will not be getting into treatment modalities for VAD patients here, but we will show you an awesome ultrasound video of a conscious VAD patient in VF. Enjoy!

Bradydysrhythmias in Syncope

A 1997 German study revealed that approximately 3-10% (depending on the ED facility) of syncope patients that were evaluated in the ED experienced syncope as a result of bradycardia.

Common causes of bradycardia:

Ischemia

Beta/Calcium Channel Blocker, digoxin, or amiodarone toxicity

Hypoxia (primarily in kids)

Electrolyte imbalance; i.e. hypo/hyperkalemia and hypocalcemia

Increased vagal tone (particularly in high performance athletes)

Sick sinus syndrome is typically found in the elderly, children with congenital heart defects, and individuals with down syndrome.

Tetralogy of Fallot repair in children can often lead to 2nd Degree Type I

2nd Degree Type II and Complete heart block are most often caused by infarction.

While a simple sinus bradycardia can absolutely cause syncope, the major culprits are sick sinus syndrome and high degree heart blocks (Second degree Type II and Third degree)

Image credit Life in the Fast Lane

Image credit: ALS Training

Rule of 15s

The Rule of 15s is essentially where 15% of these life-threatening events present with syncope as a primary symptom. (Lemonick, 2010)

Acute Myocardial Infarction

Pulmonary Embolism

Abdominal Aortic Aneurysm

Aortic Dissection

Ectopic Pregnancy

GI Hemorrhage

Subarachnoid Hemorrhage

CHESS Criteria

This is an argument for point of care ultrasound and lab testing in EMS. It’s time for us to start progressing into this and push for this being standard of care.

Glucose and Syncope

Syncope as a result of hypoglycemia is fairly rare; a 2011 study in the Journal of Clinical Medicine found that “only 1.9% of insulin-using diabetics experienced syncope”.

There are other diabetic issues that can be linked to syncope; i.e. hypovolemia from significant hyperglycemia, etc.